System of telegraph distribution



Dec. 2, 1924.

l.. M. PoTTs SYSTEM OF TELEGR'APH DISTRIBUTION Filed March 3l, 1919 5 Sheets-Sheet 2 a www. QN www .llllillll illlllllllilillllll llllllllllllllllllll l \iWKHlillIlIlllIlllllIIIIIllIIIIIIIIIIIIIIIIIIIIH` l lmf /Nr/ENOR.

A TTORNEY.

Dec. 2, 1924. 1,517,381

l.. M. PoTTs SYSTEM OF' TELEGRAPH DISTRIBUTION' Filed March 31, 1919 5 Sheets-Sheet 5 NI/ENTOR.

ATTORNEY.

Patented Dec. 2, 1924. i f 1,517,381

UNITED STATES 'PATENT OFFICE.

LOUIS M. POTTS, F BALTIMORE, MARYLAND, ASSIGNOR, BY MESNE ASSIGNMENTS, TO AMERICAN TELEPHONE AND TELEGRAPH COMPANY, OF NEW YORK, N. Y., A CORPORATION 0F NEW YORK.

SYSTEM 0F TELEGRAPH DISTRIBUTION.

Application filed March 31, 1919. Serial No. 286,540.

To c?! anic/n. it may concern.' ments not here referred to will be more par- Be it known that I, Louis M. Porrs, a cititicularly described in the accoinpanying text Zen ot thc United States, residing at Baltiand pointed out inthe claims. more, State ot' Maryland, have invented cer- In order to more fully describe my said 65 tain new and useful Improvements in Sysinvention reference will be had to the foltems of Telegraph Distribution, vot which lowing drawings, wherein, the following is a speciiication. Figure 1 shows a transmitting substation This invention relates to improvements in and a central station receiving from a subsystems of telegraph distribution and relates station and retransmitting to another cen- 6o particularly to the use of a single trunk line tral station.

b v several subscribers tor vindependent com- Figure 2 shows a central station receiving niunication between selected pairs of sta.- from another central station and retransmitl tions. The invention contemplates operating ting to a substation and a substation receivtlie trunk line in multiplex bya synchronous ing from a central. 55 5 method and operating the branch lines con- Figure 3 shows schematically a double necting the subscribers to the central office multiplex and two substations connected to by a method not involving continuously syneach terminal of the multiplex. chronized apparatus. I am aware that sys- Figure i shows the time intervals on the tems of telegraphic distribution have been transmitting branch. 7o proposed for the use of a multiplex line by a Figure 5 shows a signal on the transmitnumber of subscribers. For example, YPatting branch. ent No. 699,574 for improvements in tele- Figure 6 shows the time interval on the graphic distribution, granted to H. H. -Rowtrunk line. land, administratrix of H. A. Rowland, May Figure 7 shows the current on the trunk 6, 1902, proposed a method of distributing line when no code signals are being transmitthe different channels of a synchronous multed. tiplex to different stations. Patent No. Figure 8 shows the same signal as in Fig. 704,928 t'or telegraphic distribution, granted 5 on the trunk line. i to H. H. Rowland, administratrix of H. A. lFigure 9 shows the time intervals on the imvland, July 15, 1902, and Patent 715,696, receiving branch.

t'or telegraphic distribution, granted to H. F igure 10 shows the saine signal as in Fi H. Rowland. administratrix of H. A. .Row- 5 and S on the receiving branch.

land,` December 9` 1902, also a method of op Figure 11 shows the curve characteristic eration which involves the use of continuousof the transmitter operating cam. 3 3 lv synchronized apparatus at all the sta- In Figure 1 all the appa atus to the lett tions. The use otl continuously synchronized of the broken line is located at station X and apparatus at sub-stations is undesirable since represents the transmitting part of the appathc services ot a skilled attendant are reratus. It is to be understood, however, that quired for the maintenance oi." the apparatus. receiving apparatus is also located at each ot 40 The present invention proposes to use a the sub-stations. Transmitting apparatus is method on the branch lines which does not shown at one sub-station and receiving apinvolve the use of continuously synchronized paratus at the other, it not being considered apparatus and therefore a more practical necessary to show duplex operation as the system for telegraphic distribution. method of duplexing is well known in the .'15 The particular embodiment of the invenart. All the apparatus to the right oiE the tion here described proposes to employ autobroken line in Figure 1 represents the appamatic transmission by perforated tape at the ratus at the central station M. Apparatus is substation, and includes a novel method of here shown to receive from sub-statioii X control ot the tape transmitter from central and retransmit to central station M1 (Figure ma :30 as well as novel methods o't` relaying at cen- 2). It will also be understood that in practral, all of which as well as other improvctice at station M there will be apparatus for transmitting to sub-station X similar to the apparatus located at M1. To the left of the dotted line in Figure 2 is apparatus located at central M1 to receive the signals from central. M and to retransmit them to substation X1. It will be understood that at the station M1 there is apparatus similar' to that at M to receive signals from substation X1 and to retransmit them to central M. To the right of the broken line in Figure 2 is shown apparatus at sub-station X1 to receive the signals transmitted from central M1. It is understood, as in the previous cases that there is located at X1 transinitting apparatus similar to that shown at sub-station X.

The code used is one wherein .live equal time intervals are allowed to each signal. and impulses are sent in all combinations to forni a code. Such a code is wel] known in the art. Reference may be had to my U. S. Patent 1,229,202.

Speed contro Z.

At each of the stations `there is a suitable automatic means of regulating the speed of the motors which drive. the distributors, a method of control by a centrifugally operated contact at substations X and X1 and a method of control by an electrically driven tuning fork at cent-rals M and Ml is here shown and at the station M1 there is shown means to correct the phase of the tuning fork with respect to the line signals and thus synchronize the apparatus at the two central stations M and M1. The distributing apparatus at the substations X and X1 is stopped at the end of each signal and started at the beginning of each signal under the control of the apparatus at centrals M and M1, thus keeping the distribut-l ing apparatus at the substations in phase with the apparatus at the central. The method of tuning fork speed control shown is fully described in my U. S. Patent 1,201,- 621 and will be only briefly described here.

At substation X there is a motor 1, which through gears 2 and 3 drives shaft All, the functions ot which will be later described. The shaft 5 of motor 1 carries rigidly fast thereto a sleeve 6 and a sleeve 7 adapted to slide longitudinally thereon. One or more flexible springs 8 have one end fast to sleeve 6 and the other fast to sleeve 7 and in the centre of each is rigidly fastened a Weight 9. Sleeve 7 carries on the centre of its face an insulating tip 10 against which presses a spring 11 carrying on its tip a contact 12. Adjacent to spring 11 is mounted a similar spring 13 carrying a contact 14. The electrical connections are as follows: One terminal of the field and one armature brush of motor 1 are connected to the positive source of current supply (it is to be noted `that all the sources oli current supply at each station are connected to one source except in the case of the signallingcurrent). The other terminal of the field is connected direct to the negative source and the other armature brush through resistance 15 to negative. Contact 14 is connected to negative and contact 12 is tapped to the end of resistance 15 where it connects to the brush of motor 1. As motor 1 rotates weights 9 will have a tendency to move out and slide sleeve 7 longitudinally on shaft 5 and thus open and close contacts 12 and 14 and shunt or remove the shunt from resistance 15 and so regulate the amount ot current flowing in the armature of motor 1. By properly choosing the springs 8, and weights 9 and adjusting contacts 12 and 14 the speed of motor 1 may be made whatever is desired. The relation of the speed of motor l to the other apparatus will be fully explained later.

At central M is a motor 16 which, through gears 17 and 18, drives the brush arm 1.() which carries two trailers 20 and 21. bearing on collecting ring 22 and a segmented ring 23. Alternate segments of ring 23 are connected together and connected respectively to contacts 24 and 25, between which vibrates a tongue 26 adapted to alternately engage contacts 24 and 25. Tongue 26 is carried on one prong of a tuning 'fork 27. An electro-magnet 28 has one terminal connected through a resistance 29 to the positive terminal of the direct current source of supply. The other terminal of magnet 28 connects to contact 30. In its normal position contact 26 touches contact 30 and thus closes the circuit of magnet 28 and causes magnet 28 to attract the prongs of tuning :Bork 27 and open the circuit of magnet 28 at contacts 26 and 30 and thus allow the prongs to spring open again. The continued action of magnet 28 and contacts 26 and 30 will cause fork 27 to vibrate con tinuously. @ne terminal oi5 the field and one armature brush of motor 16 is com'leeted directly to the positive terminal, of the cur rent supply, the other terminal of the lield is connected to negative an d the other arm a ture brush is connected through a resista nec 31 to the negative terminal of the current supply and a point between resistance 81 and the brush 32 of motor 16 is connected to collecting ring 22. It will be noted that as the brush 21 passes over successive segments of segmented ring 23 and as contact 26 alternately engages contacts 24 and 25 the resistance 31 will be shunted at rapidly recurring intervals and the motor armature will be receiving current during certain intervals only through resistance 81 and at other intervals will receive current directly from the negative source. The length of the intervals during which the resistance 31 is shunted will depend upon the phase re- (lll lation between `the vibra-tion .of the timing fork 27 and the rotation of brushes 20 and 21. The speed 'of the motor having been so regl'llated that it runs at approxiu-iately such a speed -as to canse the brush 21 to pass from one segment to another on ring 23 in the interval required for the fork 27 to pass from one contact V24 lto the other 25, the motor will come up to approximately the correct speed and will vquickly assume such a phase position that the motor will automatically receive the correct amount ot cnrl'ent to drive it at a speed corresponding to the rate ot the tuning forli. It the motor tends to go too tast. for example, due to a rise of voltage, the length ot the inti-rvals during which the resistance 31V is short rircuited will be decreased, the v:unount ott rurrent flowing into the ino-tor will be decreased and the speed will be maintained. Any other tendencies to speed change will be similarly compensated for.

It is to be noted that segmented ring 23 has twice as many segments as the number of unit impulses transmitted `during one revolution of the brush arm 19. The reason tor this number of. segments in ring 23 i-s that the timing fork 27 must always be in the same phase position at each reversal of the line current so that the correcting impulses may always operate in the same phase of the tuning fork, as more fully explained in my Patent 1,201,621 previously referred to.

At central M1 there is located an electrically driven tuning fork 33, electric motor 34, brush arm 35, driven through gears 36 and 37 by motor 34. Trailer brushes 3S and 39 pass over collecting ring 40 and segmented ring 41. Segmented ring 41 has the same number .of segments as ring 23. Alternate Segments of ring 41 are connected to the contacts 42 and 43 which are alternately engaged by a tongue 44, carried by tuning for 33. O )eratinfr mao'net 45 of tunin' fork 33 b C b has one terminal connected to vibrating tongue 46 of main line relay 47 connected in trunk line 48 and operated by the current passing over said line. The other terminal ot magnet is connected midway between two condensers 49 and 50, the other terminal olf condenser 50 being connected to the negative supply terminal and the other terminal of condenser 49 being connected through a resistance 51 to the positive supply terminal.

The last mentioned terminals of condensers 49 and 50 are also connected to contacts 52 and 53 of relay 47. lhen tongue 46 passes from cont-act 52 to 53 or vice versa due to a reversal of the line current condensers 49 and 50 are charged and discharged through magnet 45. The impulses so formed at succeeding reversals of the line current maintained the motion of fork 33 in phase with the reversals ot' the line current.

Scgmented ring 41, ygears 36 and 37, and tuning fork being identical with the corresponding parts at cent-ral M, brush arm will move in synchronism with brush arm 19 at station M. The operation ot vt Transmission fr0/71| (substation.

At station X vis shown an automatic transmitter cont-rolled by perforated tape, any other method of transmission may ol course be used. This method is shown as one way of carrying Iout the invention. The automatic transnii-tter comprises live slides 58 to 58. These slides carry on their up end pins 59-59e adapted to engage the under surface of the perforated paper strip 60. The paper strip 6() has a central row or perfor-ations 61 called feed holes. A series of holes 62a have previously been perforated in any suitable manner in the tape in various combinations to represent the signals to be successively transmitted and are so arranged on the tape with respect to the feed holes 61 that, as the tape is moved along step by step by a mechanism described below, the pertorations will successively come into alignment with the corresponding pins 59 to 59e. The perforated tape passes aver a cylinder 62 carrying a row ef equally spaced pins 63 adapted to engage the feed holesI 61. Cylinder 62 has mounted on one end a ratchet wheel 64, a pawl 65 engages ratchet wheel 64 and is pivoted to an arm 66. Pawl 65 is pressed into engagement with ratchet 64 by spring 67 and arm 66 is held upward by a spring 68. Pivoted to arm 66 is a link 69 the other end oi which is pivoted to an arm 70, which is in turn nivoted at a point 71 (see Fig. l1). Arm 71 engages the ycircumference oi a disc 72 which carries a cam projection 73. Disc 72 is rotated intermittently by means later described. As disc 7 2 rotated the high part 73 of cam 72 will engage arm 70, push it downward, turn arm 66 about its pivot and cause pawl to engage ratchet wheel 64 and advance cylinder 62 one step and thereby paper strip 6() will be advanced one step, or the distance between succeeding groups of peritorations 62. .lust as disc 72 comes to rest arm 70 will rise and with it link 69, arm 66 and pawl Pawl will then be allowed to engage the next tooth in ratchet 64. By the repetition of this process paper strip 60 is advanced step by step. On the opposite end of cylinder 62 is a star wheel 74, a correcting arm 75, whose wedge shaped tip is pressed by spring 76 into the notches in star wheel 74, thus iusurllO ing a positive stopping position for tape 60 so that perforations 61 will be in alignment with corresponding pins 59il to 59e.

Slides 58l to 58e are each pressed upward by individual springs 77. The slides 58a to 58e carry horizontal arms 78 which project under the arm 66. As arm 66 is moved up and down by the action of the cam 73 the pins 59EL to 59e are successively moved away from the paper strip 60 and allowed to engage with the paper under tension of springs 77. Slides 58a to 58e also carry arms 79 which carry insulated tips 80a to 80e. The tips 80L to 80e in their downward position engage a series of stops 81;L to 81's and in their up position a series of contacts 82 to 82e. When arm 66 rises and allows pins 59*iL to 59e to move upward and if any pin 59Il to 59e engages a portion of the paper containing no perforations corresponding contact 80a to 80e will remain in engagement with the corresponding lower contact 81a to 81e. If, however, any pin 59a to 59e engages a perforated portion of strip 60 the corresponding contact 80a to 80e will engage the corresponding upper contact 82a to 82e. It will be noted then that as paper strip 60 is stepped along the contacts 80a to 80e will successively assume combinations of positions corresponding to the combinations of perforations 61 in strip 60. A more complete description of the action of the transe to be operated by a magnet 91.

mitting contacts is given later.

Gear 3 is rigidly attached to shaft 4. Fast to shaft 4 are two collars 83 and 84 and mounted loosely on shaft 4 is disc 72, a spring 85 presses at one end against collar 84 and at the other end against disc 72, thus creating a pressure between disc7 2 and collar 83, consequently as shaft 4 is continuously rotated by motor 1 disc 72 will tend to rotate. Disc 72 carries an insulated arm 86. The tip of arm 86 engages arm 87 pivoted about point 88 and normally held against stop 89 by spring 90. When arm 87 is against stop 89 arm 86 will be prevented from rotating. Arm 87 however is adapted Magnet 91 has one terminal connection through a resistance 92 to the positive terminal. The other terminal of magnet 91 is connected to contact 93 of neutral relay 94. Tongue 95 of relay 94 is connected to negative. Spring 96 normally holds tongue 86 against stop 97. One terminal of the coil 98 is connected to ground, through a switch 99 the function of which will be described later. The other terminal of coil 98 is connected to segment 100 of segmented ring 101. Segmented ring 101 is so oriented that a trailer brush 102 stops on segment 100 when the tip of arm 86 engages arm 87. Connected to arm 86 is another trailer brush 103 adapted to engage collecting ring 104. Collecting ring 104 is connected to branch line 105. Segmented ring 101 contains six equal segments. The remaining segments 106a to 106e are connected to the corresponding contacts 80u to 80e. Contacts 82a to 82e are all connected to ground. Line passes to central and connects through relays 107, 108 and 109 to one pole of generator 110, the other terminal of which connects to ground.

The mechanical details having been described and the electrical connections traced the operation of transmitting from substation X to central M will be briefly described. It will be assumed that the tip of arm 86 engages arm 87. A circuit will now be completed from the positive pole of generator 110 through relays 109 and 107 as later dr:- scribed, collecting ring 104, trailer brush 103, arm 86, trailer brush 102, segment 100l coil 98, switch 99 to ground and back to the negative brush of generator 110. Magnet 98 will be energized, tongue 95 willengage contact 93 and thus complete a circuit from positive through resistance 92, coil 91, contact 93, tongue 95 to negative. Magnet 91 will be energized, arm 87 attracted and disengaged from the tip of arm 86. Arm 86 and trailer brushes 102 and 103 will rotate with shaft 4. As trailer brush 102 passes from segment 100 the circuit of coil 98 will be broken and thereby the circuit of magnet 91. Arm 87 will return to stop 89 under tension of spring 90 and will bel in a position to stop arm 86 upon the completion of one revolution. As trailer brush 102 passes to segment 106a current will be transmitted to line or not de ending upon whether the corresponding pin 59 has been prevented from rising by the paper or has been allowed to rise in consequence of being opposite a perforation 61a. If pin 59a is opposite a perforation a circuit will be completed as follows: from the positive termiI nal of generator 110 relays 109 and 107, collecting ring 104, trailer brush 103, arm 86, trailer brush 102, segment 106, contacts 80, 82, to ground. If pin 59a engages an unperforated portion of paper strip 60 the circuit lwill be open at contact 82a. The remaining circuits may be similarly tread and successive impulses will be transmitted on line 105 dependent upon the combination of perforations engaged by pins 59a to 59e. It will be observedv that as arm 86 makes successive revolutions successive code signals each preceded by a start impulse not represented by a pin 59a to 59e will be transmitted on line 105 and relay 109 will be operated in a corresponding manner.

Reception at central from substation and retransmzsswa t0 alista-at cent/ral.

At central M, in addition to the brush arm 19, brush arms 111, 112 and 113, all insulated from one another and from brush arm 19 are driven by motor 16, through gears 17 Cil and 18. Brush arm 111 carries two trailers 114 and 115. Trailer 114 engages collecting ring 116 which is connected tothe forward contact 117 of neutral relay 1.09. Tong-ue 118 of relay 109 is held against its back stop by spring 119v and is connected to the negative terminal of the direct current source. Trailer 115 engages segmented ring 120. The n'ietal segments of ring 120 occupy about one-half of the commntator circumference, the remainder being made up of insulation. The shortened segments permit the receiving relays to use only the central portion of ythe received impulses so that if the impulses are mutilated the margin of operation is increased. Segmented ring 120 has seven segments while the transmitting segment. ring 101 at sub-station X has six segments. The speeds of motors 1 and 16,. the ratio of gears 2-3 and 17-18 and the number of segments in commutator 3 and the construction of the centrifugal governor mounted on shaft 5 are so chosenl that the trailer brush 102 will pass from the centre .of one segment to the centre of the next succeeding segment on ring 101 in the same interval as that occupied by trailer brush 115 in passing from the centre of one segment to the next succeeding segment on ring 120. Segmented ring 120 has one more segment than segmented ring 101 due to the fact that trailer brush 115 rotates continuously, While trailer brush 102 stops between each signal. The extra segment in segmented ring 120 allows the time interval necessary for the stopping and starting of trailer brush 102. By this arrangement, While vmotors 1 and 16 do not have their speed corrected with respect to one another but are merely regulated to approximately the same speed, trailer brushes 102 and 115 will pass over corresponding segments at the same time, since brush arm 86 is started at the beginning of each signal with an exact relation to brush arm 115 and during the interval of a single revolution they can get out Very little.

it station M there is a series of polarized relays 121a to 121e. The forward coils of relays 121SL to 121e are connected to succeeding segments of segmented ring 120. Two segments of ring 120` are idle. One corresponds to the so-called starting impulse and the other to the idle interval between succeeding intervals which allows for the starting and stopping of brush arm 86. The remaining terminals of the forward coils 122 to 122'3 are all connected together and through a resistance 123 to the positive direct current source. All of the back contacts 124a to 124e of relays 122L to 122e are connected together and through a resista-nce 125 to the positive pole of a generator 126, the other pole of which is connected to ground. All ofthe forward contacts ,127a to Y1,27e are connected together and through a resistance,

128 to the negative pole of generator 129, the other pole of which ,is connected to ground. The tongues 130a to 130C of relays 122a to 122eare connected to live consecutive Segments of segmented ring 131. Segmented ring 131 contains ten segments, five of which are used for transmitting the code signals received from substation X, the remaining would be used for another substation, for example, Y in Fig. 3. In case it is desired to operate the line at a different multiplicity the number of segments in this commutator would be correspondingly changed. For example, fifteen would give a triple and twenty a` quadruple. Tongue 130a is connected to segment 132e, being the seventh segment counting from the top of segmented ring 131. It is necessary that the relation of the segments of rings 131 and 120 shall be such that the operation of`v relays 121a to 121e Will notv interfere with the transn'iission by splitting signals. The relation of these segments will be more readily understood by referring to Figures 4 and 6 which are so ar anged that corresponding time intervals are shown in vertical lines. Brush arm 112 carries trailer brushes 133 and 134,` trailer brush 133 passes over collecting ring 135 which is connected to the negative source of direct current. Trailer brush 134 passes over segmented ring 136. Ring 136 has ten segments and is called the local impulse ring. The circuit for returning the tongues 13.0n to 130e to their back stops after the signal has been transmitted Will now be traced. From positive source through resistance 137 through back coil of relay 107 (the function of this relay will be later described), back coil of relays 121b and 121, segment 138 of segmented ring 136, trailer brush 134, brush arm 112, trailer brush 133, collecting ring 135 to negative. The returning circuit for the remaining relays is traced as follows: positive source through resistance 139 to back coils of relays 121e, 1211, 121c to segment 140 of segmented ring 136, trailer brush 134, brush arm 112, trailer brush 133, collecting ring 135 to negative. It is necessary to return the relays 121EL and 121b at a different time from relays 121s, 121d and 121e, for the reason that there is no time during which some one of the relays 121a to 121e is not either receiving or sending a signal. so that all the relays iannot be returned simultaneously The relays 121a and 121b are returned at a time when they are neither sending nor receiving signals and so 'with relays 121, 12,1(1 and 121e.

The connections and functions of relays 107 and 108 Will now be explained. 1t is necessary that trailers 102 and 115 shall pass over corresponding segments of rings 101 and 120 at the same time, or, in other Words, that trailer brush 102 shall be started at the beginning of a signal by an impulse sent when trailer' brush 115 is passing over segment 141. Relays 107 and 108 erform this function. Relay 108 is a neutra relay. Its circuit is traced as follows: positive through a resistance 142, coil 143, switch 144, segment 145, trailer brush 134, brush arm 112, trailer brush 133, collecting ring 135, to negative. It will be noted that by this arrangement when trailer brush 134 reaches segment 145 the above circuit will be closed and tongue 146 will make contact with contact 147 and close the line circuit through contacts 146, 147 and forward coil 148 of polarized relay 107, provided switch 99 at substation X is closed and trailer brush 102 is on segment 100. Tongue 149 of relay 107 will then go forward and make contact with contact 150 and relay 107 being a polarized relay the line 105 will remain closed at central M until trailer brush 134 reaches segment 138 of ring 136. lfVhen such is the case a circuit will be closed as previously described through the back coil 151 of relay 107v and the line will be again opened at contacts 149 and 150. If when trailer 134 reaches segment 145 the switch 144 at station M is open the relay 108 will not operate and brush arm 86 will then-stop so that trailer brush 102 is on segment 100 and will not again start until switch 144 is closed and will even then not start until trailer brush 134 reaches segment 145 on ring 136 so that the proper relation between the rotation of brush arms 86 and 111 will be maintained. It is to be noted that the transmission can thus be stopped at central M without splitting signals since the line cannot be opened until the signal is complete.

At station X there is a switch 99 which performs a similar function. Switches 99 and 144 then provide means at both central M and the substation X for starting and stopping the transmission without mutilation of the signals.

By the apparatus and electrical connection previously described relays 121a to 121e are successively set in combinations corresponding to the successive groups of perforations 61 in paper strip 60. The relays 121n to 121c if on their back stops transmit to line 48 a positive current which may be traced. as follows: positivepole of genifrrator 126, resistance 125, back contact 124, tongue 130", segment 132", trailer lgnfush 152, brush arm 113, trailer brush 153, collecting ring 1.54 to line 48, relay 47 see Figure 2), relay 153 to ground and back to the negative terminal of generator 126. ,If tongue 130a is against its front contact the circuit will be traced as follows: negative terminal of generator 129, resistance 128, front Contact 127, tongue 130iL and as previously traced and a negative impulse will be transmitted to lne. Itwill be noted that when all the relays 121l to 121e are back positive current 'lays 169d and 169( are provided.

will be sent to line. The five other segments of segmented rin@ 131 not used for the transmission descrlbed would connect to relays belonging to another substation, which would transmit to line negative impulses when the relays are against their back stops so that when no code signals are being transmitted to line from the substation 'there will be a normal current on line as shown in Figure 7. The current sent for the different groups of segments is different so that there will be a reversal of current on the line even when no code signals are being sent. This reversal is essential for the correction of the rate of tuning fork 33 and consequently essential to the maintenance of synchronism between arms 19 and 35, as eX- plained above.

Reception. fr0/m, central at dista/nt central and retransmission to desta/nt substance.

At central M1 there is a set of polarized relays 156a to 156e which have one terminal `of their coils connected to segments 157a to 157e of segmented ring 158 and have their other terminals connected together and through the coils of a polarized relay 159 'to an intermediate point 160 of resistance collecting ring 165. Arm 166, which is fast to but insulated from arm 35, carries trailer brushes 167 and 168 which pass over collect ing ring 165 and segmented ring 158. It will be noted that as brush arm 166 rotates relays 156*L to 156e will receive a positive or a negative impulse depending upon whether tongue 164 is against contact 162 or 163. If tongue 164 is against contact 162 the relays will always receive negative impulses and will be held against their back stops. If, however, tongue 164 is against contact 163 the col-iesponding relays 156a to 156e will be sent against their forward contacts. lt will be .noted that, by this .u'rangemeut, the relays 156 to 156c willlie operated. in successive combinations corresponding to the signals transmitted over line 48 and according to the successive comliiinations of :odc perforal'ions 61 in paper strip 60. ln order that sufficient time may be allowed for the retransmission of the signals before the next signal is received additional polarized re- 'lhere is also provided additional polarized relays 170. the function of which will be later explained. The forward coils of relays 1695, 169e and 170 are connected through resistances 171, 172 and 173 to the positive source of current. The other terminals of the forward coil of those relays are connected to the forward con- Contact `162 of Cul tacts 17e-l, 171c and 175. The tongue 176 is connected to segment 177 of local impulse ring 178 and the tongue176E is connected to segment 179 of local impulse rin-g 178. Brush arm 180 carries a trailer brush 181 which passes over segmented ring 178 and trailer brush 182J which passes over collecting ring 183. connected to negative. lt will be noted that as brush arm 180 rotates impulses will be transmitted through segments 177 and 179 to the forward coils of relays 169 and 169C when tongues 176" and 176e are aga-inst their forward stops. The operation of relays 169 and 169e will throw their tongues 18-1 and 181u against their forward stops 185 and 185C. The retransmission takes place from the contacts of relays 1563, 156", 156, and from the contacts of the auxiliary relays 169 and 169". The relays 169d and 169e store the D and E impulses for transmission during' the time that the relays 156 and 156e are being set for the next succeeding signal. Figures 6 and 9 show the time relations between the impulses received and relays 156 to 156 and the retransmitted impulses. The tongues 170, 170b, 170, 181 and 184e are all connected together and through resistance 186 to the positive pole of generator 187 and to ground. The forward contacts 188, 188", 188, 185d and 185 are connected to segments 189 to 189 of segmented ring 190. Segmented ring 190 contains seven segments and for the same reason as explained in connectie-n with segmented ring 120 and need not be further referred to here. Engaging segmented ring 190 is a trailer brush 191 carried by brush arm 192' which also carries another trailer brush 193 which passes over collecting ring 194. It will be noted that brush arm 192 rotates a circuit will be successively partially closed which may be traced as follows: generator 187, resistance 186, tongue 17 0a, forward con-y tact 188, segment V189?, trailer brush 191, brush arm 192, trailer brush 193, collecting ring 194, branch line 195, coil of relay 196, to ground and back to the other pole of genera-tor 187 and similarly the circuits for the other impulses may be traced.

By the apparatus and connections so far descrilfied it will be noted that there may be transmitted over line 195 to relay 196` successive code impulses corresponding to the impulses received by the relays 156*l to 156. However, for the operation of the apparatus at sub-station X1. it is necessary to precede each group of code signals by a start impulse so that the impulses transmitted over line 195 will be the same as those originally transmitted over line 105. Relays 159 and 170 perform the function ofv controlling this impulse. It will be noted' that relay 159 being connected in the common wire of all the relays 1561- to 156'e and being a polarized relay that, if all the relays- 156* to- 156e re'- ceive impulses corresponding to no code signal tongue 197 will remain against its back stop, while if any one of the relays 1562L to 156e receives an impulse to carry it forward tongue 197 will be carried against its front stop 175. However, tongue 197 will immediately return to its back stop since tongue 197 is given bias by a spring 198. Then tongue 197 goes against its forward contact 175 a circuit will be completed as follows: positive terminal, resistance 173, forward coil of relay 170, forward contact 175. tongue 197 to negative. Tongue 199 will thus be carried to its forward contact 200 and being a polarized relay will remain there until it receivesa returning impulse. Forward contact 2900 is connected to seg'- ment 201 of segmented ring 190. Segment- 201 is the st-art segment and immediately precedes the segment 189% If relay tongue 199 is forward an impulse will be transmitted to line 195' and relay 196 through segment 201 in a manner similar to that described in connection' with the A impulse and relay 156e. After been transmitted the tongue 199 is returned to its back stop along with tongues18il and 184e by a circuit completed as follows: resistance 202, back coils of relays 170. 18'1-e and 184, segment 203, trailer brush 181, arm 180, trailer brush 182, collecting ring 183, to negative. When relay 170 is returned after sending the start impulse relays 184 and 184e are being returned for the immediately preceding signal ready to be reset for the signal, the transmission of which has just been started.

It will be noted that by the operation of the devices previously described there will be transmitted on line 195 a signal as shown in Figure 10 (the figure' assumes that a signal composed of B and E impulses has been sent) and which is identical with the signal shown in F igure 5 transmitted over the original lineI 105 except that there is a certain time lag to allow for the operation of the various relays. It is to be noted that when the signal was transferred from line 105 to main line 48 that only the code elements of the signal were' retransmitted and the start impulse7 was not retransmitted. while in the case of the transfer of the signal from lineA 48 to line 195 the start impulse" was again inserted. It also to bennoted that in casev none of the relays 156d to 15 receive code impulses relay 159 will not be operated, in consequence' relay 170 will fail to operate and' no impulses will be transmitted on line 195 to relay 196.

fastenedto V ag discI L04. butl in'sulated" therefrom. Disc 204- is mounted loosely on draft the start impulse has Cri 205 which is rigidly attached to gear 57.

`Rigidly attached to shaft 205 is a disc 206 against which is pressed disc 204 by spring 207, the other end of spring 207 pressing against a sleeve 208, rigidly attached to shaft 205. By this pressure friction will be maintained between disc 204 and disc 206 and as shaft 205 is driven by motor 54 there will be a tendency for arm 203 to rotate. However, arm 203 is normally prevented from rotation by arm 209 which is held against stop 210 by spring 211 and arm 203 remains at rest with a tendency to rotate except when arm 209 is moved, as explained later. Arm 203 carries two trailer brushes 212 and 213. Tra-iler brush 212 passes over collecting ring 214 which is connected to the forward contact 215 of relay 196. The tongue 216 of relay 196 is connected to negative. Trailer brush 213 passes over segmented ring 217. The circumference of segmented ring 21.7 is half metal and half insulation for the reasons previously eX- plained in connection with ring 125. Segment 218 upon which trailer brush 213 normally rests connects to one terminal of one magnet 219, the other terminal of which connects through resistance 220 to positive. The remaining segments 221a to 221e are connected to one terminal of a series of magnets 222a to 222", the other terminals of which magnets are connected together and through resistance 223 to positive.

The operation of receiving signals at substation X1 will now be described. When relay 196 is operated by code signals on line 195 tongue 216 will engage contact 215 and will complete a circuit as follows: positive terminal, resistance 220, magnet 219, segment 218, trailer brush 213, brush arm 203, trailer brush 212, collecting ring 214, contact 215, tongue 216, to negative. Magnet 219 will thus be energized and attract arm 209 and release brush arm 203 and allow it to make a complete revolution. When trailer brush 213 reaches segment 221,a a circuit may be traced as follows, provided the signal being transmitted involves the A element, positive terminal, resistance 223, magnet 2223, segment 2211*, trailer brush 213 and as previously described in connection with the start impulse. 1f the signal being transmitted does not contain the A. element the circuit will be opened and magnet 222L will not be operated. ln a sin'iilar manner the other magnets 222b to 222o may be operated. The magnets 222 to 222e may be the selecting magnets for any suitable rccording mechanism. For example, they may be the magnets in my co-pending application, Serial Number The operation of the various parts having been described in detail, the transmission of a'signal from substation X will be very briefly outlined. 1t will be assumed that the apparatus at central M and M is operating in synchronisin and the apparatus at X and X are operating at the correct speed as explained under speed control. 1t will also be assumed that to start with the switch 144 at central M is closed and the switch 99 at substation X is open. In such a case relay 108 at central M will operate at each revolution of the distributor. It will be assumed now that the pins 59a and 59e will be opposite a portion of the paper where there are perforations 61a corresponding to the impulses B and E. If switch 99 is closed a start impulse will be transmitted on line 105 as soon as trailer brush 111 reaches segment 141. Magnet 91 will then be operated, trailer 86 will start to rotate and relay 107 will close and keep the circuit closed at central. M for the duration of the signal period and a signal like that shown in Figure 5 will be transmitted on line 105 and relay 109 will be operated in a corresponding manner. By means of segmented ring 141 the bank of relays 121 to 121'3 will be operated according to the signals sent, that :is the B and E relays will send their tongues against their forward stops and through segmented ring 131 a signal will be transmitted on line 48 like that shown in Figure 8 and relay 155 will be operated in a corresponding manner. Through distributing ring 158 the series of relays 156a to 156e will be operated according to the signals sent, that is the B and E relays will be sent against their forward stops. Relay 159 will also operate and in turn operate relay 170 and relays 169D and 169E will have their tongues sent against their forward stops to store the D and E impulses for transmission, while the relays 156D and 156E are being set for the next signal. Through segmented ring 190 and relays 156, 1561, 156, 1691, 1.69e and 170 impulses will be transmitted on line 1,95 like Figure 10 and relay 196 will be operated in a corresponding manner. The impulses transmitted by relay 170 will operate magnet 219 and start brush arm 203 in rotation. Segmented ring 270 will distribute the impulses to the series of magnets 222a to 222 and operate them according to the signal sent, that is the B and E magnets will be operated.

l claim:

1. A telegraph syslen. comprising a main i station at which is localm'l a multiplex synchronous distrilnitor and a distant ln'anch station at which located an intermittently operating distributor, a line connecting said stations. means at said main station includ- 2. In a telegraph system, a telegraph circuit, means located at one end of said circuit to transmit on said circuit combinations of impulses to form code signals, a. series of relays at the other end of said circuit, means to successively set said relays in combination corresponding to the successive code impulses transmitted, a second circuit, means controlled by said series of relays to retransmit said code signals on said second mentioned circuit, and means comprising one or more relays to store one or more of the elementary impulses of said code signals for retransmission while the corresponding relay or relays of the first series is being set for the next signal.

3. A telegraph system, a line, a distributor connected to said line, a master transmitter, comprising a Contact mechanism, a signal storage member, means for advancing said signal storage member, a contact controlling member, means for controlling said contact mechanism, and an all mechanical means between said transmitter and said distributor for imparting a step by step motion to said advancing means and for operating said controlling means.

4. In a telegraph syste-m operative on the five unit or Baudet code, a main station at which is located a multiplex synchronous distributor, a branch station at which is located a periodically rotating distributor, a line connecting said stations, means including a plurality of storing relays for receiving and storing groups of impulses and means including a part of said multiplex distributor for retransmitting the stored impulses to said branch station.

In a telegraph system, a distributor, an automatic transmitter comprising a switch contact, tape controlled members for opertween said distributor' and transmitter and effective on each revolution of said distributor for imparting a step-by-step motion to said tape.

7. In combination, a rotary distributor and a transmitter, comprising a switch contact, a tape. perforated in accordance with code combinations of signal impulse, members controlled by said tape for operating said switch contact, and an all mechanical means between said distributor and said transmitter and operated directly by said distributor for causing the advancement of said tape step by step.

8. In combination, a periodically rotating distributor, a transmitter comprising a plurality of switch contacts, a perforated tape, members controlled by said tape for operating said switch contacts, and an all mechanical means between said distributor and said transmitter and operated directly by said distributor for causing an intermittent advancement of said tape for each revolution of said distributor.

In testimony whereof I aiiix my signature.

LOUIS M. POTTS. 

